Adhesive labels and tapes are typically made up of substrates that are coated with pressure sensitive adhesives (PSAs). In order for the PSA to not stick to a substrate prior to desired placement and application, a liner, or “backing paper,” may be used. This separable liner is usually relatively easy to remove and is often sent to a landfill. Thus, this method and means is inherently environmentally unfriendly and a potentially unnecessary cost.
Other means have been explored by researchers to avoid the problem of backing paper waste. These methods place the release coating on the surface of the paper or film label facestock opposite to the PSA and the construction is self-wound like tape. There are many deficiencies with this style of label construction; the most prominent issue is dealing with exposed PSA in equipment not designed for it.
Another strategy for eliminating the liner is to use heat activated PSAs in place of the standard PSA in the label construction. This style of label theoretically does not require any form of extra release agent since the PSA is substantially non-tacky after coating the PSA and through converting steps such as printing and slitting, but the PSA is heated above the activation temperature prior to application to a substrate (bottle, box, etc) which causes it to become tacky. Current systems are flawed due to high levels of low molecular weight additives such as tackifiers and plasticizers which can migrate and cause undesirable effects. In addition, these systems often prematurely activate when stored at elevated temperatures causing the roll of label construction to be discarded.